Power on an electric grid for a particular region is generally produced via a plurality of distinct sources at a plurality of locations. The total demand for power by the collective end users on a grid varies temporally at a rate unmatched by the rate at which power production sources respond. Specifically, the rates of changes in power production are typically too slow to precisely match electricity demand increases and decreases. While systems may be implemented to watch demand and to alter, curtail, or increase production in response to the changes in demand, the inequality in the rate changes between demand and production generally cause fluctuations in the frequency of the grid power.
Frequency of the grid power varies at least temporarily as load and generation change. These variations tend to be in sub-hertz (i.e. 0.5 Hz) range on systems operating at 60 Hz or 50 Hz. More specifically, an overload in demand on the system typically causes the overall system frequency to decrease, and a significant reduction in demand typically causes the overall system frequency to increase.
The slow response time in responding to fluctuations in supply and demand on an electrical grid leads to system inefficiencies, wasted power, and dirty electricity (electricity at frequencies other than the primary frequencies).